JEE Main 2021PhysicsAtomic PhysicsMediumMCQ

JEE Main 2021 — Atomic Physics Question with Solution

JEE Main 2021 (26 Feb Shift 2)

Question

The recoil speed of a hydrogen atom after it emits a photon in going from n=5 state to n=5 state will be

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Show full solutionCorrect option: A
Correct answer
A4.17 m s-1

Step-by-step explanation

ΔE Releases when photon going from n=5 to n=ΔE

=13.6-0.54 eV=13.06 eV

Pi=Pf (By linear momentum conservation)

0=hλ-Mv=VRecoil=hλM        ...1

& ΔE=hcλ=hcλM×M⇒McVRecoil

VRecoil =ΔEMc=13.06×1.6×10-191.67×10-27×3×108=4.17 m s-1

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About this question

This is a previous-year question from JEE Main 2021, covering the Atomic Physics chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.